Liquid crystal displays (LCD) function by controlling the polarization state of display components, essentially at the pixel level. Light, typically white and emitted by a BLU source behind (from the perspective of a viewer) the LCD components, is polarized and illuminates the display components from their rear. LCD components that are in a transmissive state with respect thereto allow the polarized backlight to pass, and components that are in a non-transmissive state are correspondingly opaque.
Modern BLUs may have multiple light emitting components. For example, HDR displays may use an array of white light emitting diodes (LED). The brightness of the BLU components' emissions may be controlled to achieve acceptable HDR performance. For example, the emission intensity of one or more of the BLU components may be modulated in relation to a video input, e.g., signals that change the transmissivity state of the display components.